Schizophrenia is a neuropsychiatric and neurodevelopmental disorder. Is a chronic disease where psychological, social, and cognitive functions are crucial, severely impaired and highly cost-effective. The world prevalence is approximately 1% in all societies. As well as positive symptoms such as hallucinations and delusions, negative symptoms such as emotional withdrawal, impairments in cognitive functions such as in attention, learning and memory can be observed.

The cause of the disease is not fully known. Continuous exposure to an adverse family or social environment in individuals with genetic predisposition might causes abnormalities in brain structure and biochemistry. The complex pathophysiology of schizophrenia is not fully understood also. Neurotransmitters, such as dopamine, serotonin, GABA, glutamate and acetylcholine are known to contribute to the pathophysiology of the disease.

Eugen Bleuler used the term schizophrenia for the first time in 1908 and distinguished the effects of the disease into main and secondary symptoms. The main symptoms, according to Bleuler, are the symptoms that can be found in every schizophrenia patient, such as impairment in affect, ambivalence, autism, disturbance in associations. In the secondary group, symptoms such as delusions, illusions, and hallucinations can be also seen in other mental illnesses.

Today, the definitions made by DSM-IV and ICD-10 are used for the diagnosis of schizophrenia. According to the DSM-IV guidelines, to diagnose schizophrenia, there must be present at least two of the main symptoms for at least a month.

In schizophrenia, disorders in perception and thinking abilities also lead to changes and distortions in the person’s behavior. These distortions lead to the deterioration of the perception of outside and realism of the person by establishing a new world for himself. Schizophrenia is seen in every society and every socio-economic class. There is no significant difference between females and males, which usually occurs at young ages in both genders.

Symptoms of Schizophrenia

Symptoms in schizophrenia have a fluctuating course. Schizophrenia covers a heterogeneous spectrum of cognitive, behavioral, and emotional dysfunctions. The main symptoms of schizophrenia are due to the inability to integrate separated neural processes in distributed brain regions. There are several symptoms in the pathogenesis of the disease. Individuals with schizophrenia will differ in terms of most clinical features.

Symptoms, findings, and signs related to the thought flow, content, experience, expression of emotions, perception, and cognitive functions can be seen. The most common symptom in acute schizophrenia is lack of insight. Various and widespread positive or negative symptoms of the disease can be seen. Positive symptoms include hallucinations, distress, suspicion, distrust, hostility, delusions, hypersensitivity to sound and colors, excessive or disorganized speech, rhymed speech and disconnection in expression.

Negative symptoms include emotional withdrawal, apathy, paucity of speech, catatonic state and cognition impairment. Emotional inexpressiveness, lack of spontaneity, insensitivity, asociality, poverty of speech and anhedonia can be seen. The increase in psychotic symptoms can be associated with dopaminergic activation.

Symptoms usually begin in puberty or young adulthood. It is seen more frequently in regions that receive immigrants. Frequency, response to treatment and repeatability of symptoms may differ from patient to patient. Similar findings can be observed with diseases such as bipolar disorder and autism.

The most widely used classification system for the diagnosis of schizophrenia is the Diagnostic and Statistical Classification of Mental Disorders of the American Psychiatric Association (DSM). Diagnosis includes all symptoms in different combinations and impaired occupational or social functionality. What distinguishes schizophrenia from other psychotic mood disorders is that it requires hallucinations and delusions in the absence of mood episodes. The sum of mood episodes should be in only a small period during the total duration of the active and residual periods of the disease.

Treatment of Schizophrenia

There is no cure for schizophrenia; it can be controlled by medications. Drug treatment, psychotherapy, social, and family support should be implemented together. Antipsychotic drugs are being used in the treatment of schizophrenia. These are effective in relieving negative and cognitive symptoms while reducing positive symptoms but do not offer a definite cure. Complex medication might be needed to treat schizophrenia  because blocking dopaminergic systems may be effective for delusions and hallucinations symptoms but not sufficient for disabling cognitive and motivational symptoms.

Imaging of Schizophrenia

MR imaging is widely used to detect the structural abnormalities of the brain. The advanced MR methods, such as fMRI, resting-state fMRI and DTI that is used today, can be more helpful in terms of functionality and connectivity of the schizophrenia. Positron emission tomography (PET) is also widely used in schizophrenia and provides information about regions with functional impairment in the brain.

Connectivity in Schizophrenia

Neurodegenerative and neurodevelopmental approaches are essential to understand what is leading to schizophrenia today. The studies have not been able to reveal which region of the brain is the primary cause of this disease. Schizophrenia is characterized by impaired functional conduction pathways or abnormal integration, defined as functional dysconnectivity or disability integration between distant brain regions. A study conducted by Liu et al showed that different brain regions might be related to connectivity and message transmission disruption.

The left middle temporal gyrus, bilateral middle cingulate cortex, right paracentral lobule, right thalamus and bilateral cerebellar hemispheres were found to have decreased functional connectivity in subjects with schizophrenia. Damaraju and his colleagues in their recent study showed hyper-connectivity between the thalamus and sensory networks as well as more hypo-connectivity between the sensory networks from all modalities in a schizophrenia patient. Some studies have shown inconsistency between hyper and hypo-linked areas in the brain.

What Causes Schizophrenia?

Medical and mental health professionals have not yet determined conclusively what causes the development of the schizophrenic condition. However, researchers believe that a combination of genetic makeup, brain chemistry, and the environment contributes to the development of the schizophrenic condition.

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